Fundamental versus solitonic description of D3 branes

Type IIB string theory expanded around D3 brane backgrounds describes the d ynamics of D3 branes as solitonic objects. On the other hand, there is a fu ndamental description of them via Polchinski's open strings with Dirichlet boundary conditions. Since these two descriptions describe the dynamics of the same objects, D3 branes, it is natural to believe that they are dual. T herefore at this level, we have a string-string duality as opposed to a str ing-field theory duality. Once we take the same limits in both descriptions , the Maldacena conjecture in its weaker form follows. We try to make this viewpoint precise and study the implication of it for the stronger form of the Maldacena conjecture. (C) 1999 Published by Elsevier Science B.V. All r ights reserved.